1. Field of the Invention
The present invention relates generally to temperature-compensation structures.
2. Description of the Related Art
Efficient temperature-compensation networks can provide considerable value by improving the performance of a variety of important systems. One system example is a liquid crystal display that is formed with active arrays of thin film transistors. Display panels for this type of display are typically referred to as thin film transistor, liquid crystal display panels or TFT LCD panels. These panels include a large number of display pixels that are generally arranged in rows and columns between a pair of glass substrates which are each covered with a sheet of polarizer film.
Each pixel actually comprises three color subpixels which are each formed by positioning a color filter (either red, green or blue) and a transparent pixel electrode on opposite inner faces of the glass substrates, filling the space between with a liquid crystal, and coupling the drain of a TFT to a storage capacitor via the pixel electrode. At an operational refresh rate (e.g., 60 Hz), an activation voltage is applied to the gate of the TFT while an image signal is applied to its source.
An image voltage is thus applied to the liquid crystal and momentarily held by the storage capacitor. In response to the image voltage, the liquid crystal rotates the polarization of passing light (originating, for example, in a backlight) which, in combination with the polarization of the polarizer films, adjusts the brightness of the light emanating from the respective subpixel. An exemplary TFT LCD panel may be arranged with 768 rows and 1024 columns so that it comprises 2,359,296 subpixels and an equal number of TFT's.
Unfortunately, the performance of TFT LCD panels degrades at temperature extremes because important display parameters (e.g., TFT threshold voltage and liquid crystal viscosity) vary over temperature. This temperature degradation can be significantly reduced with the information provided by temperature-compensation networks whose configuration preferably facilitates their inclusion within panel integrated circuits.